Liquid crystal display device and driving method thereof

ABSTRACT

Disclosed are an LCD device and a driving method thereof, which save the manufacturing cost that is expended by the application of four-color (RGBW) sub-pixels, and enhance an aperture ratio and brightness, thus increasing display quality. The LCD device includes an upper substrate, a lower substrate, and a liquid crystal layer. A plurality of R, G, B and W color filters are formed at the upper substrate. In the lower substrate, a plurality of R, G, B and W sub-pixels are formed in respective regions defined by intersection of a plurality of gate lines and data lines. The liquid crystal layer is formed between the upper substrate and the lower substrate. Each of the pixels is configure with three-color sub-pixels of the R, G, B and W sub-pixels. Pixels of the plurality of pixels including a W sub-pixel share a one-color sub-pixel included in a pixel adjacent thereto, and display a color image.

The present patent document is a divisional of U.S. patent applicationSer. No. 14/873,911, filed Oct. 2, 2015, which is a divisional of U.S.patent application Ser. No. 13/339,157, filed Dec. 28, 2011, whichclaims benefit to the Korean Patent Application No. 10-2011-0012985,filed on Feb. 14, 2011, which applications are hereby incorporated byreference in their entireties for all purposes as if fully set forthherein.

BACKGROUND Field of the Invention

The present disclosure relates to a Liquid Crystal Display (LCD) device,and more particularly, an LCD device and a driving method thereof, whichsave the manufacturing cost that is expended by the application offour-color (RGBW) sub-pixels, and enhance an aperture ratio andbrightness, thus increasing display quality.

Discussion of the Related Art

In LCD devices, manufacturing technology has been advanced, drivabilityof a driving means is good, low power is consumed, high quality isrealized, and a large screen is realized. Therefore, LCD devices arebeing popularized, and application fields for LCD devices arecontinuously expanding.

FIG. 1 is a diagram illustrating a pixel structure, which includes RGBsub-pixels of a related art LCD device. FIG. 1 illustrates one unitpixel 10 of a plurality of pixels that are formed in a matrix type, in aliquid crystal panel. Hereinafter, the unit pixel is referred to as apixel.

Referring to FIG. 1, in a related art LCD device, the one pixel 10 isconfigured with three-color sub-pixels, namely, a red (R) sub-pixel 12,a green (G) sub-pixel 14 and a blue (B) sub-pixel 16. The LCD deviceadjusts the transmittance of light, irradiated from a backlight unitonto each sub-pixel, to display a color image.

In the related art LCD device, light emitted from a light source of thebacklight unit is transmitted through RGB color filters that are formedat an upper substrate, whereby brightness is degraded. The degradationof brightness is a main cause that degrades the display quality of animage.

FIG. 2 is a diagram illustrating a pixel structure, which includes RGBWsub-pixels of a related art LCD device. FIG. 3 is a diagram illustratingan RGBW quad pixel structure of a related art LCD device.

Referring to FIG. 2, a pixel structure 20 including RGBW sub-pixelsfurther includes a white (W) sub-pixel 28, in addition to the Rsub-pixel 22, G sub-pixel 24 and B sub-pixel 26. The pixel structure 20has been proposed for solving the limitation of the pixel structure ofFIG. 1 where brightness is degraded.

Furthermore, as illustrated in FIG. 3, a quad pixel structure 30 whichincludes RGBW sub-pixels has been proposed, and further includes a Wsub-pixel 30, in addition to the existing R sub-pixel 32, G sub-pixel 34and B sub-pixel 36. In the quad pixel structure 30, the four-colorsub-pixels 32, 34, 36 and 38 are arranged in a quad structure.

In the related art LCD device having the pixel structure 20 of FIG. 2 orthe quad pixel structure 30 of FIG. 3, the W sub-pixel 28 or 38increases brightness of light emitted from each pixel.

The brightness has been increased by applying the pixel structure 20 orthe quad pixel structure 30. However, the purity of RGB colors becomeslower, causing pure color darkness.

Moreover, a Thin Film Transistor (TFT) is formed in each of foursub-pixels R, G, B and W, and consequently, an aperture ratio of eachpixel is reduced.

In the pixel structure 20 of FIG. 2, a data line is additionally formedfor supplying image data (data voltage) to the additionally disposed Wsub-pixel, causing the reduction in an aperture ratio. Also, as thenumber of data lines increases, the number of source drive ICs (D-ICs)increases, and thus, the manufacturing cost increases.

In the quad pixel structure 30 of FIG. 3, a gate line is additionallyformed compared to the existing stripe pixel structure, causing thereduction in an aperture ratio. Also, the number of gate drive ICs(G-ICs) increases in proportion to the increased number of gate lines,and thus, the manufacturing cost increases.

In regard to a manufacturing process, in the pixel structure 20 of FIG.2, a TFT mask design structure for the existing three-color (RGB) pixelstructure is applied to a process of manufacturing a lower substrateas-is.

However, a process of manufacturing an upper substrate additionallyrequires a mask for forming the W sub-pixel. Due to this reason, amanufacturing process design is changed, and thus, the manufacturingcost increases.

FIG. 4 is a diagram illustrating image data (data voltages) applied to apixel structure which includes RGBW sub-pixels of a related art LCDdevice.

Referring to FIG. 4, when image data (data voltages) are respectivelysupplied to RGBW sub-pixels by 1-dot inversion scheme, image data havingthe same polarity are respectively supplied to sub-pixels of the samecolor that are disposed on one horizontal line. Due to this reason,sub-pixels are deteriorated and crosstalk occurs, causing thedegradation of display quality.

BRIEF SUMMARY

Accordingly, the present invention is directed to provide an LCD deviceand a driving method thereof that substantially obviate one or moreproblems due to limitations and disadvantages of the related art.

An aspect of the present invention is directed to provide an LCD devicewhich can save the manufacturing cost that is expended by theapplication of four-color (RGBW) sub-pixels.

Another aspect of the present invention is directed to provide an LCDdevice, which enhances an aperture ratio and brightness when four-color(RGBW) sub-pixels are applied thereto, thus increasing display quality.

Another aspect of the present invention is directed to provide an LCDdevice in which four-color (RGBW) sub-pixels are formed without changinga manufacturing process design for the existing three-color (RGB)sub-pixels, thus saving the manufacturing cost.

Another aspect of the present invention is directed to provide an LCDdevice which controls polarities of image data (data voltages) that arerespectively supplied to sub-pixels of the same color disposed on onehorizontal line when four-color (RGBW) sub-pixels are applied thereto,thus preventing the deterioration of sub-pixels and reducing crosstalk.

In addition to the aforesaid objects of the present invention, otherfeatures and advantages of the present invention will be describedbelow, but will be clearly understood by those skilled in the art fromdescriptions below.

Additional advantages and features of the invention will be set forth inpart in the description which follows and in part will become apparentto those having ordinary skill in the art upon examination of thefollowing or may be learned from practice of the invention. Theobjectives and other advantages of the invention may be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the invention, as embodied and broadly described herein, there isprovided an LCD device including: an upper substrate in which aplurality of red (R), green (G), blue (B) and white (W) color filtersare formed; a lower substrate in which a plurality of R, G, B and Wsub-pixels are formed in respective regions defined by intersection of aplurality of gate lines and data lines; and a liquid crystal layerformed between the upper substrate and the lower substrate, wherein,each of the pixels is configure with three-color sub-pixels of the R, G,B and W sub-pixels, and pixels of the plurality of pixels including a Wsub-pixel share a one-color sub-pixel included in a pixel adjacentthereto, and display a color image.

The pixels including the W sub-pixel may share a one-color sub-pixel ofthe R, G and B sub-pixels with one or more pixels adjacent thereto, anddisplay a color image with R, G, B and W sub-pixels, the one-colorsub-pixel not being included in the pixels.

In the lower substrate, three-color (RGB) sub-pixels may be formed at aleft and a right with respect to the W sub-pixel, and a pattern of sevensub-pixels including one W sub-pixel may be repeatedly formed.

In another aspect of the present invention, there is provided a drivingmethod of an LCD device, in which a plurality of red (R), green (G),blue (B) and white (W) color filters are formed in respective regionsdefined by intersection of a plurality of gate lines and data lines,including: aligning input RGB video signals into digital image data;generating a scan signal to sequentially supply the scan signal to theR, G, B and W sub-pixels; converting the digital image data into RGBWimage data; performing sub-pixel rendering on the RGBW image data;converting the rendered RGBW image data into analog image data; andsupplying the analog image data to the R, G, B and W sub-pixels insynchronization with the scan signal to display a color image, wherein,each of the pixels is configure with three-color sub-pixels of the R, G,B and W sub-pixels, and pixels of the plurality of pixels including a Wsub-pixel share a one-color sub-pixel included in a pixel adjacentthereto, and display a color image.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiments of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 is a diagram illustrating a pixel structure which includes RGBsub-pixels of a related art LCD device;

FIG. 2 is a diagram illustrating a pixel structure which includes RGBWsub-pixels of a related art LCD device;

FIG. 3 is a diagram illustrating a quad pixel structure which includesRGBW sub-pixels of a related art LCD device;

FIG. 4 is a diagram illustrating image data (data voltages) applied to apixel structure which includes RGBW sub-pixels of a related art LCDdevice;

FIG. 5 is a diagram illustrating an LCD device according to anembodiment of the present invention;

FIG. 6 is a diagram illustrating a rendering driver of FIG. 5;

FIG. 7 is a diagram illustrating a liquid crystal panel of FIG. 5;

FIGS. 8 and 9 are diagrams illustrating a pixel structure and drivingmethod of an LCD device according to a first embodiment of the presentinvention;

FIG. 10 is a diagram illustrating a pixel structure and driving methodof an LCD device according to a second embodiment of the presentinvention;

FIG. 11 is a diagram illustrating a pixel structure and driving methodof an LCD device according to a third embodiment of the presentinvention;

FIG. 12 is a diagram illustrating a pixel structure and driving methodof an LCD device according to a fourth embodiment of the presentinvention; and

FIGS. 13 to 15 are diagrams illustrating respective image data (datavoltages) applied to pixels of an LCD device according to an embodimentof the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS AND THE PRESENTLY PREFERREDEMBODIMENTS

Reference will now be made in detail to the exemplary embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

Hereinafter, an LCD device and a driving method thereof according toembodiments of the present invention will be described in detail withreference to the accompanying drawings.

FIG. 5 is a diagram illustrating an LCD device according to anembodiment of the present invention. FIG. 6 is a diagram illustrating arendering driver of FIG. 5.

Referring to FIGS. 5 and 6, an LCD device according to an embodiment ofthe present invention includes a liquid crystal panel 100, a gate driver200, a data driver 300, a backlight unit 400, a backlight driver 500, atiming controller 600, and a rendering driver 700.

The timing controller 600 converts input video signals (data) intodigital image data R, G and B of a frame unit and supplies the digitalimage data RGB, aligned by frame unit, to the rendering driver 700 withan input timing signal TS. Herein, the timing signal TS includes avertical sync signal Vsync, a horizontal sync signal Hsync and a clocksignal CLK.

Moreover, the timing controller 600 generates a gate control signal GCSfor controlling the gate driver 200 with the vertical sync signal Vsync,horizontal sync signal Hsync and clock signal CLK. Furthermore, thetiming controller 600 generates a data control signal DCS forcontrolling the data driver 300. The timing controller 600 supplies thegate control signal GCS to the gate driver 200, and supplies the datacontrol signal DCS to the data driver 300.

Herein, the data control signal DCS may include a source start pulse(SSP), a source sampling clock (SSC), a source output enable signal(SOE), and a polarity control signal (POL).

The gate control signal GCS may include a gate start pulse (GSP), a gateshift clock (GCS), and a gate output enable signal (GOE).

Furthermore, the timing controller 600 generates a backlight controlsignal BCS for controlling a backlight, on the basis of the input videodata and timing signal TS. The timing controller 600 supplies thebacklight control signal BCS to the backlight driver 500.

The rendering driver 700 of FIG. 6 converts the digital image data,inputted from the timing controller 600, into RGBW image data. Therendering driver 700 performs sub-pixel rendering on the RGBW image dataand supplied the rendered image data to the data driver 300.

For this end, the rendering driver 700 includes a memory (line buffer)710, a data converting unit 720, and a Sub-Pixel Rendering (SPR) unit(sub-pixel rendering means) 730.

The memory 710 stores the digital image data R, G and B, aligned byframe unit in the timing controller 600, by line unit. The memory 710supplies the digital image data R, G and B, stored by line unit, to thedata converting unit 720.

The data converting unit 720 converts image data such that the imagedata (data voltages), which are supplied to a plurality of pixels formedin the liquid crystal panel 100, are rendered to be suitable for a pixelstructure. In this case, the image data may be converted incorrespondence with each of the pixels. As an example, the dataconverting unit 720 may convert RGB type image data into the RGBW imagedata and supply the RGBW image data to the SPR unit 730.

The SPR unit 730 performs sub-pixel rendering on the RGBW image datasupplied from the data converting unit 720, and supplies the renderedRGBW image data to the data driver 300/

Herein, the SPR unit 730 may perform sub-pixel rendering on the RGBWimage data supplied from the data converting unit 720 as follows.

As an example, the SPR unit 730 may perform sub-pixel rendering on theRGBW image data, by horizontal line unit or vertical line unit.

As another example, the SPR unit 730 may perform sub-pixel rendering onthe RGBW image data, by vertical and horizontal line unit.

As another example, the SPR unit 730 may perform sub-pixel rendering onthe RGBW image data, by pixel block unit that is configured with acertain number of pixels or entire pixel unit that is driven during oneframe.

In FIG. 5, the rendering driver 700 is illustrated and has beendescribed above as an independent element in the LCD device according toan embodiment of the present invention. However, this is one embodimentof the present invention.

In another embodiment of the present invention, the rendering driver 700may be included in the other element of the LCD device. As an example,the rendering driver 700 may be included in the timing controller 600.

The gate driver 200 generates a scan signal (gate driving signal) fordriving a thin film transistor that is formed in each of the pixels, onthe basis of the gate control signal GCS from the timing controller 600.

The scan signal generated by the gate driver 200 is sequentiallysupplied to a plurality of gate lines GL1 to GLn during one frameperiod. A thin film transistor formed in each sub-pixel is driven by thescan signal that is sequentially supplied to the gate lines GL1 to GLn,and thus, switching is performed in each pixel.

The data driver 300 includes a plurality of source drive ICs, each ofwhich converts the image data (RGBW-rendered image data), supplied fromthe rendering driver 700, into analog image data, namely, data voltages.

The data driver 300 supplies data voltages for one horizontal line to aplurality of data lines DL1 to DLm at a time when a thin film transistorof each sub-pixel is turned on, on the basis of the data control signalDCS from the timing controller 600.

Herewith, a common voltage Vcom is supplied to a plurality of commonelectrodes that are respectively formed at the pixels. An electric fieldis generated in each pixel by a data voltage and common voltage suppliedto each pixel. By aligning liquid crystal with the electric field thathas been generated in each pixel, the light transmittance of each pixelmay be controlled.

The liquid crystal panel 100 cannot self-emit light, and thus displaysan image with light supplied from the backlight unit 400.

The backlight unit 400 irradiates light on the liquid crystal panel 100,and includes a plurality of backlights and optical members.

Herein, the backlights may be configured with a plurality of one typelight sources or a plurality of two or more type light sources amongCold Cathode Fluorescent Lamps (CCFLs), External Electrode FluorescentLamps (EEFL), and Light Emitting Diodes (LEDs).

The optical members include a prism sheet, a diffuser sheet, a DualBrightness Enhancement Film (DBEF), and a light guide panel (ordiffusive plate).

The backlight driver 500 controls driving (on-off) of a plurality ofbacklights, and may control the on-off time, duty ratio and brightnessof the backlights on the basis of a backlight control signal BCSsupplied from the timing controller 600.

As an example, the backlight driver 500 may generate a driving signal(pulse width modulation signal (PWM) when the backlights are LEDs) forcontrolling brightness of the backlights, and control the duty ratio andbrightness of the backlights with the driving signal.

The following description will be made with reference to FIG. 7 on apixel structure of an LCD device according to an embodiment of thepresent invention that shares three-color sub-pixels of four-color(RGBW) sub-pixels and one sub-pixel of four-color (RGBW) sub-pixelsincluded in an adjacent pixel to display a color image.

FIG. 7 is a diagram illustrating a liquid crystal panel of FIG. 5. FIGS.8 and 9 are diagrams illustrating a pixel structure and driving methodof an LCD device according to a first embodiment of the presentinvention. In FIG. 8, a sub-pixel is illustrated as having one domain.In FIG. 9, a sub-pixel is illustrated as having a multi-domain.

Referring to FIGS. 7 to 9, the liquid crystal panel 100 includes anupper substrate 140 and a lower substrate 150 that are coupled to eachother with a liquid crystal layer 160 therebetween.

The gate lines GL1 to GLn and data lines DL1 to DLm are formed tointersect each other, at the lower substrate 150. A pixel array 152 isformed in a region that is defined by the intersection of the gate lineand date line.

The pixel array 152 includes R, G, B and W sub-pixels, each of whichincludes a thin film transistor being a switching element, a storagecapacitor Cst, a pixel electrode, and a common electrode.

Herein, the thin film transistor has a gate connected to a gate line, asource connected to a data line, and a drain connected to the pixelelectrode.

When the liquid crystal panel 100 has an In-Plane Switching (IPS) mode,the common electrodes are formed at the lower substrate 150. When theliquid crystal panel 100 has a Vertical Alignment (VA) mode, the commonelectrodes may be formed at the upper substrate 140.

The upper substrate 140 includes a plurality of R, G, B and W colorfilters 142, a plurality of black matrixes 144, and an overcoat layer146.

The black matrix 144 is formed between adjacent filters of the R, G, Band W color filters 142 to divide regions of respective sub-pixels, andprevents light interference between adjacent sub-pixels.

The overcoat layer 146 is formed on the color filters 142 and planarizesthe upper substrate 140.

The liquid crystal panel 100 including the above-described elementsaligns liquid crystal with an electric field that is generated by a datavoltage (i.e., a pixel voltage) supplied to a sub-pixel and a commonvoltage Vcom supplied to a common electrode.

The transmittance of light from the backlight unit 400 is controlled bythe alignment of liquid crystal. Light transmitted through the R, G, Band W color filters 142 is irradiated as inherent color light, therebydisplaying a color image.

Herein, the color filters 142 formed at the upper substrate 140 areformed in correspondence with the respective sub-pixels formed at thelower substrate 150, and the liquid crystal panel 100 has a structurewhere a color filter pattern configured with seven color filters isrepeatedly formed on a horizontal line and a vertical line.

Specifically, one color filter pattern is configured with seven colorfilters for respectively displaying R, G, B, W, R, G and B color light.

The liquid crystal panel 100 has a structure where R, G, B, W, R, G andB color filters are repeatedly formed as one group on a horizontal lineand a vertical line.

That is, in the upper substrate 140, one color filter pattern isconfigured with seven color filters 142 (i.e., R, G, B, W, R, G and Bcolor filters) and formed in a matrix type.

Herein, the W color filter may be formed in various types during aprocess of manufacturing the upper substrate 140.

As an example, the W color filter may be formed of a transparent resin.As another example, white light from the backlight unit 400 may beirradiated as-is without forming a separate resin in a white pixelregion.

As illustrated in FIG. 8, four-color (RGBW) sub-pixels are repeatedlyformed on a horizontal line and a vertical line, at the lower substrate150. Herein, three-color (RGB) sub-pixels are formed at the left and theright with respect to the W sub-pixel. Therefore, seven sub-pixelsincluding one W sub-pixel are repeatedly disposed at the lower substrate150.

Specifically, seven color filters for respectively displaying R, G, B,W, R, G and B colors are repeatedly formed as one group on a horizontalline and a vertical line.

One pixel is configured with three sub-pixels among the R, G, B and Wsub-pixels. For example, one pixel is configured with R, G and Bsub-pixels or R, G and W sub-pixels or R, B and W sub-pixels or G, B andW sub-pixels. A pixel including a W sub-pixel does not include one ofthe R, G and B sub-pixels. In this case, the pixel including the Wsub-pixel may share at least one sub-pixel of R, G and B sub-pixelsadjacent thereto, when the pixel including the W sub-pixel displays animage.

Herein, pixels formed on an odd-numbered horizontal line and pixelsformed on an even-numbered horizontal line may differ in arrangementtype of sub-pixels configuring a pixel.

A first embodiment of the present invention will be described below withreference to FIGS. 8 and 9.

Among a plurality of pixels formed on one horizontal line, a first pixel111, a third pixel 113, a fifth pixel 115, and a seventh pixel 117 maybe configured with R, G and B sub-pixels. A second pixel 112, a fourthpixel 114, and a sixth pixel 116 may be configured with three sub-pixelsthat include a W sub-pixel and two of R, G and B sub-pixels.

In order to display a color image, each pixel is required to includethree-color (RGB) sub-pixels.

Herein, the second pixel 112, fourth pixel 114, and sixth pixel 116include a W sub-pixel, and thus do not include a specific sub-pixel(displaying one color) of R, G and B sub-pixels.

Therefore, to display a color image, the second pixel 112, fourth pixel114, and sixth pixel 116 including a W sub-pixel share a one-colorsub-pixel (not included therein) of three-color sub-pixels that areincluded in a pixel adjacent thereto.

In detail, the second pixel 112 configured with W, R, and G sub-pixelsshares a B sub-pixel that is included in each of the first and thirdsub-pixels 111 and 113 adjacent thereto in a horizontal direction.Therefore, the second pixel 112 is configured with W, R, and Gsub-pixels, but in driving, the second pixel 112 may share the Bsub-pixels that are respectively included in the first and thirdsub-pixels 111 and 113 adjacent thereto, and thus display a color imagewith the R, G, B and W sub-pixels.

The fourth pixel 114 configured with B, W, and R sub-pixels shares a Gsub-pixel that is included in each of the third and fifth sub-pixels 113and 115 adjacent thereto in a horizontal direction. Therefore, thefourth pixel 114 is configured with B, W, and R sub-pixels, but indriving, the fourth pixel 114 may share the G sub-pixels that arerespectively included in the third and fifth sub-pixels 113 and 115adjacent thereto, and thus display a color image with the R, G, B and Wsub-pixels.

The sixth pixel 116 configured with G, B, and W sub-pixels shares an Rsub-pixel that is included in each of the fifth and seventh sub-pixels115 and 117 adjacent thereto in a horizontal direction. Therefore, thesixth pixel 116 is configured with G, B and W sub-pixels, but indriving, the sixth pixel 116 may share the R sub-pixels that arerespectively included in the fifth and seventh sub-pixels 115 and 117adjacent thereto, and thus display a color image with the R, G, B and Wsub-pixels.

As described above, in the LCD device according to the first embodimentof the present invention, one pixel is configured with three sub-pixelsamong R, G, B and W sub-pixels. Furthermore, pixels including a Wsub-pixel may share one-color sub-pixel included in a pixel adjacentthereto, and thus display a color image.

Comparing the present invention with the related art where one pixel isconfigured with four (RGBW) sub-pixels, a measured result on whitebrightness is shown in Table (1) below.

TABLE 1 The present The related art invention (RGBW) (RGBWRGB) RemarkWhite brightness 100% 140% Enhanced white brightness by 40%

Referring to Table (1), when realizing a white image with only R, G andB sub-pixels other than a W sub-pixel, it can be seen that the presentinvention has further enhanced white brightness by about 40% than therelated art where one pixel is configured with four (RGBW) sub-pixels.Comparing the present invention with the related art with respect to twopixels, it can be seen that the present invention has less decreasedwhite brightness than the related art.

Specifically, when realizing a white image with only R, G and Bsub-pixels without driving a W sub-pixel, the related art drives onlysix (RGBRGB) sub-pixels of eight sub-pixels without driving the othertwo W sub-pixels of the eight sub-pixels, and thus decreases brightnesscorresponding to the two W sub-pixels.

However, the present invention drives two pixels with seven sub-pixelsR, G, B, W, R, G and B. When realizing a white image without driving a Wsub-pixel, the present invention drives only six (RGBRGB) sub-pixels ofthe seven sub-pixels without driving the other one W sub-pixel of theseven sub-pixels, and thus only decreases brightness corresponding tothe one W sub-pixel.

In the description of FIGS. 8 and 9, it has been described above thatpixels formed on an odd-numbered horizontal line and pixels formed on aneven-numbered horizontal line differ in arrangement type of sub-pixels.However, this is one embodiment of the present invention. Anotherembodiment of the present invention on an arrangement structure ofsub-pixels configuring a pixel will be described below with reference toFIG. 10.

FIG. 10 is a diagram illustrating a pixel structure and driving methodof an LCD device according to a second embodiment of the presentinvention.

Referring to FIG. 10, in the LCD device according to the secondembodiment, one pixel includes three (three-color) sub-pixels offour-color (RGBW) sub-pixels. A pixel including a W sub-pixel may shareat least one sub-pixel of R, G and B sub-pixels included in pixelsadjacent thereto, and thus display an image.

Herein, pixels formed on an odd-numbered horizontal line and pixelsformed on an even-numbered horizontal line may be the same inarrangement type of sub-pixels.

Identically to the above-described first embodiment, in the LCD deviceaccording to the second embodiment, a second pixel 112, a fourth pixel114, and a sixth pixel that include a W sub-pixel may share a one-colorsub-pixel of R, G and B sub-pixels included in a pixel adjacent thereto,and thus display a color image.

In the description of FIGS. 8 and 9, it has been described above that asub-pixel of one color which is not included in R, G and B colors sharesa sub-pixel configuring a pixel adjacent thereto in a horizontaldirection, for displaying a color image of a pixel including a Wsub-pixel. However, this is one embodiment of the present invention.

Other embodiments of the present invention, in which pixels including aW sub-pixel shares a one-color sub-pixel included in pixels adjacentthereto, will be described below with reference to FIGS. 11 and 12.

FIG. 11 is a diagram illustrating a pixel structure and driving methodof an LCD device according to a third embodiment of the presentinvention.

Referring to FIG. 11, in the LCD device according to the thirdembodiment of the present invention, each pixel may share a one-colorsub-pixel (which is not included therein) of R, G and B sub-pixelsconfiguring a pixel adjacent thereto in a vertical direction, in orderfor a pixel including a W sub-pixel to display a color image.

To provide a description on pixels formed in a first row, a second pixel112, a fourth pixel 114, and a sixth pixel 116 that include a Wsub-pixel may share a one-color sub-pixel included in a pixel adjacentthereto in a vertical direction, and thus display a color image.

As an example, the second pixel 112 configured with W, R, and Gsub-pixels does not include a B sub-pixel. The second pixel 112 mayshare a B sub-pixel of an eighth pixel 122 that is formed in a secondrow to be adjacent thereto in a vertical direction, for displaying acolor image.

The fourth pixel 114 configured with B, W, and R sub-pixels does notinclude a G sub-pixel. The fourth pixel 114 may share a G sub-pixel ofan tenth pixel 124 that is formed in the second row to be adjacentthereto in a vertical direction, for displaying a color image.

The sixth pixel 116 configured with G, B, and W sub-pixels does notinclude an R sub-pixel. The sixth pixel 116 may share an R sub-pixel ofa twelfth pixel 126 that is formed in the second row to be adjacentthereto in a vertical direction, for displaying a color image.

To provide a description on pixels formed in the second row, a seventhpixel 121, a ninth pixel 123, and an eleventh pixel 125 that include a Wsub-pixel may share a one-color sub-pixel included in a pixel adjacentthereto in a vertical direction, and thus display a color image.

As an example, the seventh pixel 121 configured with W, R, and Gsub-pixels does not include a B sub-pixel. The seventh pixel 121 mayshare a B sub-pixel of the first pixel 111 that is formed in the firstrow to be adjacent thereto in a vertical direction, for displaying acolor image.

The ninth pixel 123 configured with B, W, and R sub-pixels does notinclude a G sub-pixel. The ninth pixel 123 may share a G sub-pixel ofthe third pixel 113 that is formed in the first row to be adjacentthereto in a vertical direction, for displaying a color image.

The eleventh pixel 125 configured with G, B, and W sub-pixels does notinclude an R sub-pixel. The eleventh pixel 125 may share an R sub-pixelof the fifth pixel 115 that is formed in the first row to be adjacentthereto in a vertical direction, for displaying a color image.

FIG. 12 is a diagram illustrating a pixel structure and driving methodof an LCD device according to a fourth embodiment of the presentinvention. In FIG. 12, among a plurality of pixels including a Wsub-pixel, a pixel formed in a first row is illustrated as an example. Apixel including a W sub-pixel is illustrated as sharing a one-colorsub-pixel included in a pixel adjacent thereto.

Referring to FIG. 12, in the LCD device according to the fourthembodiment of the present invention, each pixel may share a one-colorsub-pixel (which is not included therein) of R, G and B sub-pixelsconfiguring a pixel adjacent thereto in a vertical direction and ahorizontal direction, in order for a pixel including a W sub-pixel todisplay a color image.

For example, a second pixel 112 that includes W, R, and G sub-pixels butdoes not include a B sub-pixel may share a B sub-pixel included in thefirst and third pixels 111 and 113 adjacent thereto in a horizontaldirection, for displaying a color image. Furthermore, the second pixel112 may share the B sub-pixel of the eighth pixel 122 that is formed ina second row to be adjacent thereto in a vertical direction.

As described above, although the second pixel 112 including no Bsub-pixel is configured with only W, R, and G sub-pixels, the secondpixel 112 may share a B sub-pixel that is included in pixels adjacentthereto in a horizontal direction and a vertical direction, and thusdisplay a color image with R, G, B and W sub-pixels.

In the LCD device having the above-described configuration and pixelstructure, according to embodiments of the present invention, whenapplying a four-color (RGBW) sub-pixel structure including a W sub-pixelfor enhancing brightness, a pixel design and a mask for forming a pixelstructure configured with three-color (RGB) sub-pixels may be usedas-is, thus saving the manufacturing cost that is expended by applyingthe four-color (RGBW) sub-pixel structure.

In the LCD device according to embodiments of the present invention, oneW sub-pixel is formed per unit of seven sub-pixels (R, G, B, W, R, G andB), thereby displaying a color image with three-color (RGB) sub-pixels.By enhancing brightness of a pixel with a W sub-pixel, the displayquality of an image can increase. That is, by repeatedly forming apattern of seven sub-pixels including a W sub-pixel, the brightness andcolor purity of a pixel can increase.

Moreover, in the LCD device according to embodiments of the presentinvention, one pixel is configured with three sub-pixels, and thus, anaperture ratio of a pixel can more increase than the four-color (RGBW)sub-pixel structure of the related art, thereby increasing the displayquality of an image.

FIGS. 13 to 15 are diagrams illustrating respective image data (datavoltages) applied to pixels of an LCD device according to an embodimentof the present invention.

Referring to FIG. 13, as an example of supplying image data to pixels,the LCD device according to an embodiment of the present invention mayapply a 1-dot inversion scheme per one horizontal line to supply theimage data to sub-pixels.

Therefore, by alternately changing polarities of image data that aresupplied to the sub-pixels disposed on one horizontal line, the presentinvention can prevent the deterioration of sub-pixels and the generationof crosstalk.

Referring to FIG. 14, as another example of supplying image data topixels, the LCD device according to an embodiment of the presentinvention may apply the 1-dot inversion scheme for a vertical line and ahorizontal line to supply the image data to total sub-pixels.

Therefore, by alternately changing polarities of image data supplied tosub-pixels that are adjacently formed on a vertical line and ahorizontal line, the present invention can prevent the deterioration ofsub-pixels and the generation of crosstalk.

Referring to FIG. 15, as another example of supplying image data topixels, the LCD device according to an embodiment of the presentinvention may apply the 1-dot inversion scheme to the R, G and Bsub-pixels to supply the image data to the R, G and B sub-pixels. Theimage data are respectively supplied to the R, G and B sub-pixels toalternately change polarities of the image data which are supplied tosub-pixels of the same color disposed on one horizontal line orsub-pixels of the same color disposed on one vertical line. In thiscase, the LCD device according to an embodiment of the present inventionmay supply image data having the same polarity to W sub-pixels amongtotal R, G, B and W sub-pixels.

Therefore, by alternately changing polarities of image data supplied toR, G and B sub-pixels that are adjacently formed on a vertical line or ahorizontal line, the present invention can prevent the deterioration ofsub-pixels and the generation of crosstalk. Meanwhile, the image dataare respectively supplied to the R, G and B sub-pixels to alternatelychange polarities of the image data which are supplied to sub-pixels ofthe same color disposed on one horizontal line and sub-pixels of thesame color disposed on one vertical line. That is, the image date arerespectively supplied to the R, G and B sub-pixels to alternately changepolarities of the image data which are supplied to total sub-pixelsdriven during one frame period. Therefore, by alternately changingpolarities of image data supplied to R, G and B sub-pixels that areadjacently formed on a vertical line and a horizontal line, the presentinvention can prevent the deterioration of sub-pixels and the generationof crosstalk.

Herein, the polarities of image data supplied to all the sub-pixels ofFIGS. 13 to 15 may be changed by a frame inversion scheme.

By using the pixel structures of FIGS. 13 to 15 and the methods ofsupplying image data that have been described above with reference toFIGS. 13 to 15, the present invention can prevent the deterioration ofsub-pixels and the generation of crosstalk, thus increasing the displayquality of an image.

In the LCD device according to embodiments of the present invention, apixel structure is formed such that a pixel including a W sub-pixelshares a one-color sub-pixel which is included in a pixel adjacentthereto in a horizontal direction, a vertical direction, or a horizontaldirection and vertical direction, and by rendering image data of R, G, Band W sub-pixels, the brightness and color purity of a displayed imagecan increase, thus enhancing display quality.

According to the embodiments, the present invention can save themanufacturing cost that is expended by the application of the four-color(RGBW) sub-pixels.

According to the embodiments, the present invention enhances an apertureratio and brightness when the four-color (RGBW) sub-pixels are appliedthereto, and thus increase display quality.

According to the embodiments, the present invention forms the four-color(RGBW) sub-pixels and the four-color color filters without changing amanufacturing process design for the existing three-color (RGB)sub-pixels, and can save the manufacturing cost of the LCD device.

According to the embodiments, the present invention controls polaritiesof image data (data voltages) that are respectively supplied to thesub-pixels disposed on one horizontal line when the four-color (RGBW)sub-pixels are applied thereto, and thus can prevent the deteriorationof the sub-pixels and reduce crosstalk.

In addition to the aforesaid features and effects of the presentinvention, other features and effects of the present invention can benewly construed from the embodiments of the present invention.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A Liquid Crystal Display (LCD) device comprising: an upper substratein which a plurality of red (R), green (G), blue (B) and white (W) colorfilters are disposed; a lower substrate in which a plurality of R, G, Band W sub-pixels are disposed in respective regions defined byintersection of a plurality of gate lines and data lines; and a liquidcrystal layer disposed between the upper substrate and the lowersubstrate, wherein pixels comprise a first pixel having R, G and Bsub-pixels, a second pixel having R, G and W sub-pixels, a third pixelhaving R, B and W sub-pixels and fourth pixel having G, B and Wsub-pixels, and wherein the second pixel shares B sub-pixel in a pixeladjacent thereto in a vertical direction, the third pixel shares Gsub-pixel in a pixel adjacent thereto in a vertical direction, thefourth pixel shares R sub-pixel in a pixel adjacent thereto in avertical direction, and a pixel comprising a W sub-pixel is disposedbetween two pixels which each comprise R, G, and B sub-pixels.
 2. TheLCD device of claim 1, wherein the pixels disposed on an odd-numberedhorizontal line and pixels disposed on an even-numbered horizontal lineare same in arrangement type of sub-pixels configuring a pixel.
 3. TheLCD device of claim 1, wherein the pixels comprising the W sub-pixelshare a one-color sub-pixel of the R, G and B sub-pixels with one ormore pixels adjacent thereto, and display a color image with R, G, B andW sub-pixels, the one-color sub-pixel not being comprised in the pixels.4. The LCD device of claim 1, wherein the pixels comprising the Wsub-pixel share a one-color sub-pixel which is comprised in one or morepixels adjacent thereto in a vertical direction, and display a colorimage with R, G, B and W sub-pixels.
 5. The LCD device of claim 1,wherein, in the lower substrate, three-color (RGB) sub-pixels aredisposed at a left and a right with respect to the W sub-pixel, and apattern of seven sub-pixels comprising one W sub-pixel is repeatedlydisposed.
 6. The LCD device of claim 1, further comprising; a timingcontroller aligning input RGB video signals into digital image data; agate driver generating a scan signal to supply the scan signal to the R,G, B and W sub-pixels; a rendering driver converting the digital imagedata into RGBW image data, and performing sub-pixel rendering on theRGBW image data; a data driver converting the rendered RGBW image datainto analog image data to supply the analog image data to the R, G, Band W sub-pixels; and a backlight unit supplying light to the R, G, Band W sub-pixels, wherein image data are respectively supplied to the R,G and B sub-pixels to alternately change polarities of the image datawhich are supplied to total sub-pixels driven during one frame period,sub-pixels of the same color disposed on one horizontal line, orsub-pixels of the same color disposed on one vertical line.
 7. A drivingmethod of a Liquid Crystal Display (LCD) device, in which a plurality ofred (R), green (G), blue (B) and white (W) color filters are disposed inrespective regions defined by intersection of a plurality of gate linesand data lines, the driving method comprising: aligning input RGB videosignals into digital image data; generating a scan signal tosequentially supply the scan signal to the R, G, B and W sub-pixels;converting the digital image data into RGBW image data; performingsub-pixel rendering on the RGBW image data; converting the rendered RGBWimage data into analog image data; and supplying the analog image datato the R, G, B and W sub-pixels in synchronization with the scan signalto display a color image, wherein pixels comprise a first pixel havingR, G and B sub-pixels, a second pixel having R, G and W sub-pixels, athird pixel having R, B and W sub-pixels and fourth pixel having G, Band W sub-pixels, and wherein the second pixel shares B sub-pixel in apixel adjacent thereto in a vertical direction, the third pixel shares Gsub-pixel in a pixel adjacent thereto in a vertical direction, thefourth pixel shares R sub-pixel in a pixel adjacent thereto in avertical direction, and a pixel comprising a W sub-pixel is disposedbetween two pixels which each comprise R, G, and B sub-pixels.
 8. TheLCD device of claim 7, wherein, in the lower substrate, three-color(RGB) sub-pixels are disposed at a left and a right with respect to theW sub-pixel, and a pattern of seven sub-pixels comprising one Wsub-pixel is repeatedly disposed.
 9. The driving method of claim 7,wherein image data are respectively supplied to the R, G and Bsub-pixels to alternately change polarities of the image data which aresupplied to total sub-pixels driven during one frame period, sub-pixelsof the same color disposed on one horizontal line, or sub-pixels of thesame color disposed on one vertical line.